The influence of solvent on peptide conformation is being investigated with the purpose of developing a predictive understanding of the phenomena which may ultimately be useful in rational design of peptides for their biological activity. Data on conformational distributions and equilibria of selected synthetic peptides in various solvents, including especially water, are being obtained by nuclear magnetic resonance and circular cichroism spectroscopy. Conformational equilibrium data from cyclic hexapeptides are being interpreted to identify solvent and side chain effects. Crystallographic studies of some of the peptides are being made in a search for modes of water-peptide interactions. Effects of solvation are being modelled in conformational energy calculations to match the solution data. A study of chain folding in LHRH and analogs has been undertaken.